Time-sequence observations of microtubule dynamics throughout mitosis in living cell suspensions of stable transgenic Arabidopsis - Direct evidence for the origin of cortical microtubules at M/G(1) interface

Transgenic Arabidopsis thaliana, stably expressing a GFP-TUA6 fusion protei n, were subcultured in B5 medium supplemented with 2,4-D and BA, In the cel l suspensions, the microtubular changes in the mitotic cells could be monit ored by time-sequence observations using a time-lapse system of fluorescenc e microscopy. We have succeeded in following the microtubule (MT) dynamics in living cells throughout mitosis, from the late G(2) phase to early G(1) phase, and found that, at the M/G(1) interface, the cortical MTs were first ly reorganized in the perinuclear regions and then in the cortex, as we had previously suggested (Hasezawa and Nagata 1991, Nagata et al, 1994). The s ignificance of this observation on the origin of cortical MTs is discussed.